Called my cell. I didn't answer. Called back on my work line. You get an auto recording that says, "Hello and thank you for calling. If you would like to be placed on the do not call list for the number that called you, please press 1." I waited to see if there was any other option or if anything else would happen, but it just repeated the message. I tried pushing any number other than 1, and it repeated the message, and then it just said "Thank you." and hung up. Obviously a spammer trying to confirm your number exists so they can continue to spam you.